Solvent fractionation of waxcontaining mixtures



y 2, 19 2 E. w. CLARKE 2,604,431

SOLVENT FRACTIONATICN 0F WAX-CONTAINING MIXTURES Original Filed Sept. 16, 1947 EX TM SOLVENT I ADOIT/VE 2'" ADDIT/VE 4775.57 INVENTOR.

Edyar WC/ar/te New Y 1 *7/41 m-J Patented July 22, 1952 iihia, P

Me .n.

ailplication Sentem l .EXo'moNA rIoN F MIXTURES c d ar W-lGlarkeoLaur lf SnneetiLL sienor' to, The Aflanti0 ;Refinirig,Qgmpa ny, Philadely. a corporationof n n syl va n'q Q1947 frial o No i -7 1230- lDoivj an. the appl'iatin'no- 1 i b s 29 .9 Serial,

.r w n ethyl ne l ol.mqnqrme b lether.

.ufi L plietiv e 151 qiYisi pp wrangl n plicatioriserial Number 77 l, 23(), filed S e te Inber 16 v t le; 5 3 1 ent d solvent r'ra'cmohauh bf War-Containing Mixeh w en sr e a r'i'iii ia tothe de-o'iling of hydrocarbon Waxes containing 7 not'mo're' than about 70% of oil, and to thesepanfractions of difierent melting point. The process noipthelpresent .invention may-he applied-in the .o zia'eiinin lpnrification or separation. oflwaxvstocks eh t aptwa11q1i phjases ising 'th hi" heif melting Wa J frgction ..with inor amounts or j solvent and additive, and the other comprising the lower j me1t1 j VfVrac tiontvith r'najor amounts of solvent anolaglqitive, separatingthe' liduid' phases from one another, removing the solvent and additive from each. The' extraction solvent and additives employed armaylhavetaldensity.greater than'that of th wax.

. I-IpWever-mwhenw the additive. or. additives are partially immiscible qwithmthe extraction solvent :ar d a re less qensethansuch solventlornthewax, he ,ac lgiitivepr a dglitiv s will flow pountercurrent 'that'lfdufd'iihahomprising the higher melting mpr in i nitrohenzene ,and .anladditive w xifr w iqn: i' ihe sn e si f nprqcssz pnends on the .coxlt q r o Line tem atu ,,.th o ghp t thee-e t a. ion on len ;u qn. the e ul ti n;the.prop r oned,solre te qi ti 5J insect.- .a l' -nq nt f .c mtm'duQFiQni-Qt' .wex-con in e fim xturelth l a t asi i i evi tol ee tract on Qnei unt ieate r'wex...

' J l p the ot rncompr mgan'lit e inhawQ t! i 13 gn s lms lvent an Wa nin owe "than, f rea sntwezsraaw lai'hn ri r- 001 r odies ando originally p sent zait w ai lt e n ractism olvent with the itiV .Q ZQ QIZOr@PQ 'UQE L mustnot ex esgiv lyjow r the elec lv. extraction solvent at" the temperature of extrac- 30, Q n Y V. e extrac i e i t m amounts ranging jijrom L to. 53m nies'of p er o meiptilmtn et tl s ifl k. i r s d v sama he sedtnpamofi 35 rangingjrom'0.05, to 1 volume per volume of untreatepljvvaxj 7' v. 1 r ,The' ext a ction Yso ve tsi yzh a J loyedinacoordance =w1t the p sent v tion compri e n tmbe n and i t be e ev-cbnta .ing a small, amount of v ethylene glycol monol hy :31?

The so vent ad s allyl "emb y e del 1c re Won .ts cenfi tutine not --.i,:m eihenli5 b .Lql e iheext ect o 45.

yen't, comprise 'ethylerie glycol mono-methyl maintained in the system by means of heating or cooling coils or jackets, the temperatureincreasing in the direction of flow of the rafiinate or 7 higher melting wax fraction. V

The present invention may be further understood with reference to the accompanying drawing which illustrates diagrammatically a continuous extraction system suitable for carrying out the process. Referring to the drawing, a wax contaming .mixture is continuously introduced, in liquid condition, into the extraction tower I through valve controlled pipe 2 at a rate of 100 'volumes'per hour. An extraction solvent comprising nitrobenzene is continuously introduced from vessel 3 by means of valve-controlled'pipe land manifold 5 -26 to the solvent storage vessel 3 for reuse. When into the upper section of the tower below the raffinate outlet at a rate of 200 volumes per hour. The first additive comprising ethylene glycol mono-methylether is continuously introduced from vessel 6 throughvalve-controlled pipe 1 into gth extraction tower l 7 below the wax inlet at a rate of '10 volumes per hour. The second additive .also' comprising ethylene glycol mono-methylether; is, continuously introduced by valve-controlled pipe 8 intothe extraction tower I between the point of introduction of the first additive and the outlet of the extract phase, at a rate of .10 volumes per hour, such second additive being delivered from vessel 9 through pipe 10.- An in- .timate countercurrent contacting of the wax stock, the extraction solvent, and'the additives is 'efiected in tower l', a temperature gradient being maintained in the tower by means of coils ll Zthrou'ghjwhich a heating or cooling medium is circulated as required,'the temperature adjacent the top'of the tower being higher than that adjacent the bottom of the tower, the contents of the tower being entirely in the liquid phase. The wax stock, being subjected to the action of the sol- .vent and additives, is caused to separat by sol- Tvent actioninto'. two fractions, thehig'her meltingfraction wax passing upwardly through the tower together with a minor amount of dissolved v extraction solvent and additive, and being withdrawn therefrom above thelevel of the dotted line l2 representing .the higher melting wax phase relatively freeoffentrained, immiscible sol- I .vent and additive. .The ramnate phase comprising the higher melting wax and dissolved solvent and additive is passed from the top of tower I '1 through valve-controlled pipe [3 into a vacuum evaporator or still [4 wherein the'solvent and additive is removed from the higher melting wax by vaporization, thesolvent and additive vapors passing through pipe l5 into fractionating tower I6 provided with a reboiler or heating coil ll, while the higher melting waxis drawn from the bottom of evaporator I4 and delivered by valvecontrolled pipe I8 into storage vessel l9. Such wax fraction was'white in color, and had a substantially higher melting point and a lower oil -content than the original waxy mixture.

The extract phase comprising the lower melting wax fraction, color bodies, oil, and the major .portion of the extraction solvent and additives is withdrawn from the lower section of tower I beit is desired to incorporate in th nitrobenzene, small amounts of ethylene glycol mono-methyl, ether this may be accomplished by introducing the latter from vessel 6 by means of valve-controlled pipe 27. The additive, i. e., ethylene glycol monomethyl ether, separated from the nitrobenzene by fractionation in tower I6 is taken overhead as vapor by pipe 28, condensed in condenser 29 and returned by pipes 30 and 31 to vessels 6 and 9,

. respectively. A portion of the vapor streammay be' diverted through valve-controlled pipe 32, condensed in condenser 33, and the condensate returned as reflux to the top of'tower [6 by pipe'34.

Depending upon the temperature'of operation, the first additive may be introduced somewhat above the point of introduction'of'the liquefied waxy stock, for example, by means of valvecontrolled pipe 35 rather than through valvecontrolled pipe 1, in which case the second additive may be admitted through either or both of valve-controlled pipes I and 8 below the point of introduction of thewax stock. In general, the ramnate wax phase withdrawn fromthe extraction tower will contain from. 5% to 25% ofsolvent and additive, While the extract wax phasawill contain from 55% to 90% of solvent'and additive.

While, in the extraction system above described,

Ia specific combination of an extraction solvent and additives were used, it is obvious that various other combinations may be employed, depending upon the'nature of the wax stock who treated, the extraction temperatures, and the extent to which the wax stock is to be separated into components. In the event that the extraction is to be carried out in a multi-stage batch counter-current system, for example, a 4-stage system using the solvent and additives specifically set forth above, the wax stock would be introduced into the first stage extractor, the extraction solvent comprising nitrobenzene would be" introduced into the fourth stage extractor and the first additive, -i. e., ethylene glycol mono-methyl ether, would be introduced into the first stage extractor. The Second additive, ,e. g., thesame methyl ether, would be introduced into the second stage extractor. The extract phase is withdrawn from the first stage extractor, while the raffinate phase would be removed from the fourth stage extractor. The temperature would increase progressively from the first stage to the fourth stage, using the waxy stock, solvent, andaddirtives described hereinabove. It is to be understood, of course, that the quantities and composition of the solvent and of the additives maybe varied within certain'limits.

Exemplary of the various solvent andadditive materials which may be used in accordance withthis invention are the following, ;the quan- Extraction's'olvent 1 Additive 2c Additive" ethylene glycol mono-methyl other 0.1 i 0.05

v s. ethyleneglycol I 'mono-methyl ether onions vols. 4

ethylene glycol mono-methyl ether, 0.1 5:0.05' vols; "ethylene glycol mono-methyl ether' o'llimoli -vols; J

niti'cbenzene 2* 0.4 vols.

nitroben'zene 2% ethylene, glycol mono-methyl ether 23:0.4 vols.

The present invention is turtlierr illustrated by the following examples which", however'fare' not to. be construed as, limiting thejscopel'thereofzj (1) 'A' slack wax .having'a melting. point of 113 F. and. an oil; contentfof'f24l2%by weight was extracted inas'ystem similar to that "shown in the accompa yi g drawing, the extraction solvent comprising .2 volumes ofi nitroberizene, the first additive comprising 0.1 volume'ofethylcne. glycol mono-methyl ether, and the second additive comprising. 0.1 volume. of ethylene glycol mono-methyl ether. The slack wax. was introduced-into tower l by, pipe 2, thesolvent by pipe dandmanifold 5-, the first additive by pipe .I and-the second additive by pip 8. The temperaturein the extraction tower was maintained constant at 90 F. Aiter countercurrent'contacting and removal of the 'rafiinate phase fromthe top of-the tower, andthe extract phase from the bottomo'f the tower,=the solventand additives were recovered from the-wax fractions by vacuum evaporation and fractionation. The results are shown in the following tablez gg Extract Wax Weight Yield.per cent 100 52. 9 47'. 1 Melting Point F 113. l 126. 6 98. 5 Oil Content, Weight per" cent 24. 2 0. 3 51. 3 Refractive Index at 176 F... 1. 43625 1. 42895 1. 44320 A. P. I. .GI&Vl .tY;. '40. 5 42.4 l. .37. Color. Brown .White Dark Brown Firmness. Nil G'ood N' Tacltiness Poor -.:..G'ood 1 Poor Plasticity; Too Soft Good Too Soit Fiber Lengt Short Long Short Flexibility Poor Good Poor (2) The. same slack wax used in Example 1 was extracted with a different solvent but the same additives, namely, an extraction solvent comprising 2 volumes of nitrobenzene containing 2% of ethylene glycol mono-methyl ether, the first additive comprising 0.1 volume of ethylene glycol mono-methyl ether, and the second additive comprising 0.1 volume of ethylene glycol mono-methyl ether. The temperature in this extraction was held at 90 F. The results are given in the following table:

in a tower, it has been found that a tower havdistance from the"bottom of the tower.

extraction solvent is charged just-above the upper permitted to separate'from the raffinate'and ex-* tract phases, respectively. In such a't'cwe'r, the wax stockis charged at a point aboutlfi feet from the bottom thereof, or approximately the The level ofthe packing, for example, 3 4 feet from the topof'the-tower. The first additive maybe introduced adjacent the point of introduction of the wax-stock, for example, 2 feet above orbelow the wax inlet. 'Ihesecond'additive is introduced approximately 2 feet 'below the point of introduction of the first additive. These values may be altered somewhat, depending upon the towerdesign, the solvent and additives used, and the temperatures maintained at various levels in the tower. the top of the tower, and the extract phase from the bottom thereof, the extraction solvent'being more dense than the wax stock.

I claim: we

1. The method of separating a Wax-containingmixture into fractions of higher and lowermelting point, which comprises counter-currently contacting said wax cont'aining mixture inan extraction zone with an extraction solvent a'nzisol-'- vent additives at a temperature suchthat two being introducedadjacent' the point of intro-' duction of the wax containing mixture, and the second additive v being introduced between the point of introduction, of the first additive and the point of withdrawal of the lowermelting. wax fraction, thesolvent comprising 1.6 to 2.4'volum'es of nitrobenzene per volume of wax-containing mixture, the first additive comprising 0.05 to 0.15 volume of ethylene glycol mono-methyl ether per volume of wax-containing mixture, and the second additive comprising 0.05 to 0.15 volume of ethylene glycol mono-methyl ether per volume of wax-containing mixture. 7

2. The method of separating a wax-containing mixture into fractions of higher and lower melting point, which comprises counter-currently contacting said wax-containing mixture in an extraction zone with an extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction with minor amounts of solvent and additives, and the other comprising the lower melting wax fraction with major amounts of solvent and additives, separating the phases from one another, and removing the solvent and additives from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction, thefirst additive being introduced between the point of introduction of the wax-containing mixture and the point of withdrawal of the lower melting wax fraction,and the second additive being introduced between the point of introduction of the first additive and The raflinate phase is withdrawnfrom access;

the point of withdrawal of the lower melting "the, second additive comprising 0.05 to 0.15 volume of ethylene glycol mono-methyl ether per,

volume of wax-containing mixture.

3. In a method of separating a wax-containing mixture into fractions, of higher and lower. melting point; wherein the wax-containing mixture is contacted in an extraction zone with an'extrac tion solvent andsolvent additives at a. tempera ture above the melting-point butbelow the teme. perature of complete miscibility of themixtu're;

the steps which comprise introducing 1 volume of liquefied wax-containing mixture into the ex-, traction zone at a, point intermediate the points of withdrawal of the higher and lowergmelting waxes including the solvent and additive, intro-f ducing 1.6 to 2.4 volumes of extraction solvent comprisingnitrobenzene at a point adjacent the point of withdrawal of the higher melting wax fraction including solvent and additive, but intermediate said point of withdrawal and the point of introduction of the liquefied wax -con duction of the first additive and the point of,

withdrawal of the lower melting wax fraction including solvent and additive, effecting counter current contact between the liquefied wax-containing mixture and the solvent and'additives at a temperature such that two immiscible liquid phases are formed, one, phase comprising the higher melting wax fraction containing minor amounts of solvent and additives; and the other liquid phase comprisingthe lower melting wax fraction and major amounts of solvent and addie tives, the temperature in the extraction zone increasing in the direction of flow of the higher melting wax fraction, separately withdrawing the respective liquid phases from the extraction zone, and removing the. solvent and additives from each. 1 I v e .4. The method'of separating a wax-containing mixture into fractions of higher and lower melting 'point, which comprises counter-currently contacting said wax-containing mixture in an extraction zone with an 1 extraction solvent and solvent additives at a temperature such that two immiscible liquid phases are formed, one comprising the higher melting wax fraction containin'gjsolv'ent. and 'additives, and the other coinprising solvent and'additives and the lower melt-' ing waxjfraction, separ'ating'the phases from one another, and removing the solvent and additives from each, the solvent being introduced into the extraction zone near the point of withdrawal of the higher melting wax fraction, the first additive being introduced adjacent the point of introduction of the wax-containing mixture, and the second additive being introduced between the point of introduction of the first additive and the point of withdrawal of the lower melting 'wax fraction, the solvent comprising'lfi to 2.4 volumes of nitrobenzene containing 2% of ethylene'glycol mono-methyl ether per volume of wax-containing mixture, the first additive comprising 0.05 to 0.15 volume of ethylene glycol monomethyl ether per volume of wax containing mixture, andthe second additive comprising0.05 to 0.15 volume of ethylene glycol mono-methyl ether per volume of wax-containing mixture.

EDGAR W. CLARKE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Clarke Feb. 13, 1951 

1. THE METHOD OF SEPARATING A WAX-CONTAINING MIXTURE INTO FRACTIONS OF HIGHER AND LOWER MELTING POINT, WHICH COMPRISES COUNTER-CURRENTLY CONTACTING SAID WAX-CONTAINING MIXTURE IN AN EXTRACTION ZONE WITH AN EXTRACTION SOLVENT AND SOLVENT ADDITIVES AT A TEMPERATURE SUCH THAT TWO IMMISCIBLE LIQUID PHASE ARE FORMED, ONE COMPRISING THE HIGHER MELTING WAX FRACTION CONTAINING SOLVENT AND ADDITIVS, AND THE OTHER COMPRISING SOLVENT AND ADDITIVES AND THE LOWER MELTING WAX FRACTION, SEPARATING THE PHASES FROM ONE ANOTHER, AND REMOVING THE SOLVENT AND ADDITIVES FROM EACH, THE SOLVENT BEING INTRODUCED INTO THE EXTRACTION ZONE NEAR THE POINT OF WITHDRAWAL OF THE HIGHER MELTING WAX FRACTION, THE FIRST ADDITIVE BEING INTRODUCED ADJACENT THE POINT OF INTRODUCTION OF THE WAX-CONTAINING MIXTURE, AND THE SECOND ADDITIVE BEING INTRODUCED BETWEEN THE POINT OF INTRODUCTION OF THE FIRST ADDITIVE AND THE POINT OF WITHDRAWAL OF THE LOWER MELTING WAX FRACTION, THE SOLVENT COMPRISING 1.6 TO 2.4 VOLUMES OF NITROBENZENE PER VOLUME OF WAX-CONTAINING MIXTURE, THE FIRST ADDITIVE COMPRISING 0.05 TO 0.15 VOLUME OF ETHYLENE GYLCOL MONO-METHYL ETHER PER VOLUME OF WAX-CONTAINING MIXTURE, AND THE SECOND ADDITIVE COMPRISING 0.05 TO 0.15 VOLUME OF ETHYLENE GYLCOL MONO-METHYL ETHER PER VOLUME OF WAX-CONTAINING MIXTURE. 